For this article, our colleague Rik Wessels performed a life cycle assessment (LCA) example by comparing different eggs. An LCA-study shows detailed insights in the potential environmental impact of a product or service.
For the conscious consumer, supermarkets present lots of difficult choices. Do you opt for products packed in plastic packaging and go with paper packaging? What about a biological product or a product with a certain certification?
Take the egg shelves. Do you choose free-range eggs, organic eggs, or eggs with a ‘better life’ quality label? These options all say something about the way the hens live and are fed, but this does not directly say anything about the environmental impact. An LCA study provides insight into where the environmental impacts lie.
Quantify environmental impact with LCA
By using an LCA study, we take the entire product life cycle of an egg into account. The carbon footprint of a kilogram of eggs varies from approximately 2 to 4 kilograms of carbon per kilogram of product. This variation is due to a number of factors; such as the difference in the animal feed used, but also in the way in which chickens are reared. For example, organic eggs have higher carbon emissions than free-range eggs [1].
At first, this may sound contradictory. The feed of organic chickens often comes from the region, while the feed for other chickens often consists of soy. This mostly comes from South America. In addition, when growing the feed of organic chickens, no artificial fertilisers and synthetic pesticides are used [2].
However, the production of this feed is less efficient than for non-organic animal feed. Such crops fail more often or grow less quickly due to the absence of pesticides and fertilisers [3].
Hence, there are many factors that determine the environmental impact of eggs. With an LCA, these factors are clarified using different impact categories. These range from the effect on climate change due to greenhouse gas emissions to different forms of impact on human health.
The environmental hotspots of eggs
An LCA is a system approach, in which every step in the supply chain is taken into account: from cradle to grave. One of the factors in which the breeding methods differ from each other is the energy consumption. In general, more chickens in a single stable means less (thermal) energy needs to be used.
Chicken feed
Energy consumption is dwarfed, however, by the factor that contributes most to carbon emissions: chicken feed.
The carbon emissions of both broiler and laying hens are largely determined by the environmental impact of the administered feed. A chicken eats about two to three kilos of feed per kilo of eggs [4]. These chickens are often fed a mix of soy, wheat and maize. The emissions of this feed can contribute up to 90% of the total carbon footprint [5].
In addition, the feed conversion is important. The feed conversion for organic chickens is much higher than for other chickens. This means that an organic chicken has to eat more to achieve the same production of chicken meat or chicken eggs.
Land use
Another important factor, which is linked to the feed, is carbon impact due to land use change. Soy comes mainly from South America, where a large part of the production is still accompanied by the destruction of tropical rainforests. Despite the lower production efficiency, organic chicken feed has less impact on land use because less soy is used.
However, there is great methodological uncertainty about the accuracy with which the land use impact can be quantified in an LCA. This factor is therefore not included in many studies that calculate the CO2 emissions of chicken eggs. Blonk Consultants allocates an additional 1.6 kilos of CO2 emissions for land use change, but also indicates that this contains a great deal of uncertainty [6].
Manure
After the feed, manure is the largest contributor to the total CO2 emissions. In addition to CO2, chicken manure also contains a part of CH4 (methane) and N2O (laughing gas). One kilogram of methane equals approximately 25 kilograms of CO2 emissions, and one kilogram of nitrous oxide is equivalent to 298 kilograms of CO2 emissions!
Blonk Consultants has calculated that the manure storage and processing of an organic laying hen emits more CO2 than for free-range laying hens. This is mainly due to the higher protein content in the administered feed, which causes more methane and nitrous oxide to be released [5].
How to reduce impact: Kipster eggs
The company Kipster is named the most sustainable company in the Netherlands in 2020. Kipster is one of the companies that is actively working on improving animal welfare and reducing carbon emissions.
For example, the laying hens receive a mix of mainly residual flows, supplemented with a small amount of ‘high-quality’ feed. This ensures that the carbon emissions of the feed are reduced by approximately fifty percent. Despite these residual flows, the feed still contributes 77% to the company’s total carbon emissions [7].
Nevertheless, Kipster managed to reduce the impact of its eggs to 1.3 kilos of carbon per kilo of product. Taking animal welfare more into account does not necessarily have to be at the expense of the carbon footprint.
Effects of small-scale chicken farming
Kipster proves that reducing the environmental impact does not have to come at the expense of animal welfare. By using local residual flows, no soy needs to be obtained from South America. This saves carbon emissions and does not result in extra land use.
Large-scale production is of course more efficient than small-scale production. In practice, however, this does not necessarily mean that the small-scale production of chicken eggs entails a higher carbon footprint. The advantage of keeping production on a small scale is that local residual flows can be used, which is a bottleneck for large-scale production. This means that small-scale production can not only be better for the chickens, but also for the climate.
At Hen & Co they offer a unique experience in which chicken and the egg are central. In their projects, they support small-scale chicken farming at home in combination with your own vegetable garden. With such solution, you can have new pets and become partly self-sustainable.
SOURCES AND LINKS
[[1] Blonk consultants & ABN Amro. (2011). Duurzaamheid in eieren en kippenvlees. Via https://docplayer.nl/10142966-Duurzaamheid-in-eieren-en-kippenvlees.html
[2] Milieucentraal. (n.d.). Eieren. Via https://www.milieucentraal.nl/eten-en-drinken/milieubewust-eten/eieren/
[3] Mommers, J. (2015). Factcheck: ‘Kippen in de wei zijn slecht voor het milieu’. Via https://decorrespondent.nl/3219/factcheck-kippen-in-de-wei-zijn-slecht-voor-het-milieu/355827059313-879506d0
[4] Dekker, S. E. M., De Boer, I. J., Vermeij, I., Aarnink, A. J., & Koerkamp, P. G. (2011). Ecological and economic evaluation of Dutch egg production systems. Livestock Science, 139(1-2), 109-121.
[5] Blonk Consultants & ABN AMRO. (2018).
[6] Blonk Consultants. (2019). De cijfers op een rijtje. Via https://www.blonkconsultants.nl/portfolio-item/de-cijfers-op-een-rijtje/
[7] Kipster. (2020). Jaarverslag 2020. Via: https://www.kipster.nl/blog/ons-jaarverslag-2020
